1. Field of the Invention
The present invention relates to sequence controllers, and more particularly, to a sequence controller especially adapted for use with an automatic soup and beverage vending machine.
2. The Prior Art
Soup and beverage vending machines have heretofore been generally controlled by electromechanical devices, incorporating a plurality of cams for actuating a plurality of on-off switches. The cams are mounted on a common shaft for rotation together, and they actuate the switches in a fixed, predetermined sequence, to allow the device to produce a number of output signals in predetermined sequences. The times of occurrences of the signals can be modified by adjusting the angular position of the cams on the shaft, but this modification is very inexact. Typically, after each adjustment, the machine must be cycled and timed, to determine the effect which each adjustment has on operation of the system.
While such systems have been satisfactory for the limited purposes for which they are intended, they are relatively inflexible, and difficult to adjust. It is accordingly desirable to produce a system which is more flexible, and simpler and more economical to manufacture.
Another disadvantage of previous machines is their vulnerability to modification of the timing adjustments by unauthorized persons. Since the timing cams are exposed to tampering by anyone who has access to the interior of a vending machine or the like which incorporates the controller, there is little control over the actual operation of the vending machine by the machine's owner.
Yet another disadvantage results from the fact that the cam shaft must turn through the same angle during each cycle of operation, which means that all possible sequences take the full time required for the longest possible sequence. This materially decreases the vending speed of a vending machine for sequences which can be shorter in duration.